A highly selective and sensitive rhodamine B-based chemosensor for Sn4+ in water-bearing and biomaging and biosensing in zebrafish.

A novel colorimetric-fluorescent dual-mode chemosensor (JT5) based on rhodamine B has been produced for monitoring Sn4+ in the DMSO/H2O (4:1, v/v) medium. It has high sensitivity, a low detection limit, a short response time (1 s) and high stability, and can still be maintained after two weeks with the red dual fluorescence/ colorimetric response. Enhancement of red fluorescence (591 nm) and red colorimetric (567 nm) response of JT5 by Sn4+ addition. The electrostatic potential of the sensor JT5 molecule was simulated to speculate on the sensing mechanism, and the IR, mass spectrometry and 1H NMR titration were utilized to further demonstrate that JT5 was coordinated to Sn4+ with a 1:1 type, the rhodamine spironolactam ring of JT5 opens up to form a penta-membered ring with Sn4+, meanwhile, its system may have chelation enhanced fluorescence (CHEF) effect. In addition, theoretical calculations were carried out to give the energy gaps of JT5 and [JT5 + Sn4+] as well as to simulate the electronic properties of the maximal absorption peaks. Notably, the sensor JT5 was successfully applied to monitoring Sn4+ in zebrafish, and the JT5-loaded filter paper provided a solid-state platform for detecting Sn4+ by both naked eye and fluorescent methods. In summary, this work contributes to monitoring Sn4+ in organisms and solid-state materials and promotes understanding of Sn4+ functions in biological systems, environments, and solid-state materials.

Ratiometric emission of Tb(III)-functionalized Cd-based layered MOFs for portable visual detection of trace amounts of diquat in apples, potatoes and corn.

Diquat (DQ) is a typical bipyridine herbicide widely used to control weeds in fields and orchards. The severe toxicity of diquat poses a serious threat to the environment and human health. Metal-organic frameworks (MOFs) have received widespread attention due to their unique physical and chemical properties and applications in the detection of toxic and harmful substances. In this work, a two-dimensional (2D) Tb(III) functionalized MOF Tb(III)@1 (1 = [Cd(HTATB)(bimb)]n·H2O (Cd-MOF), H3TATB = 4,4',4″-triazine-2,4,6-tribenzoicacid, bimb = 1,4-bis((1H-imidazol-1-yl)methyl)benzene) has been prepared and characterized. Tb(III)@1 has excellent optical properties and high water and chemical stability. After the Tb(III) is fixed by the uncoordinated -COO- in the 1 framework, Tb(III)@1 emits the typical green fluorescence of the lanthanide ion Tb(III) through the "antenna effect". It is worth noting that Tb(III)@1 can be used as a dual emission fluorescence chemical sensor for the ratio fluorescence detection of pesticide DQ, exhibiting a relatively low detection limit of 0.06 nM and a wide detection range of 0-50 nM. After the addition of DQ, a rapid color change of Tb(III)@1 fluorescence from green to blue was observed due to the combined effects of IFE, FRET and dynamic quenching. Therefore, a simple test paper box has been designed for direct on-site determination of pesticide DQ. In addition, the developed sensor has been successfully applied to the detection of DQ in real samples (fruits a Yin-Xia Sun and Bo-Tao Ji contributed equally to this work and should be considered co-first authors.nd vegetables) with satisfactory results. The results indicate that the probe developed in this study has broad application prospects in both real sample detection and actual on-site testing.

Coordination-Driven Salamo-Salen-Salamo-Type Multinuclear Transition Metal(II) Complexes: Synthesis, Structure, Luminescence, Transformation of Configuration, and Nuclearity Induced by the Acetylacetone Anion.

A flexible polydentate Salamo-Salen-Salamo hybrid ligand H4L was designed and synthesized, which has rich pockets (salamo and salen pockets) so that it may have fascinating coordination patterns with transition metal(II) ions. Four multinuclear transition metal(II) complexes, novel butterfly-shaped homotetranuclear [Ni4(L)(µ1-OAc)2(µ1,3-OAc)2(H2O)0.5(CH3CH2OH)3.5]·4CH3CH2OH (1), helical homotrinuclear [Zn3(L)(µ1-OAc)2]·2CH3CH2OH (2), double-helical homotrinuclear [Cu2(H2L)2]·2CH3CN (3), and mononuclear [Ni(H2L)]·1.5CH3COCH3 (4), have been synthesized and characterized by single-crystal X-ray diffraction. The effects of different anions [OAc- and (O2C5H7)2-] on the complexation behavior of H4L with transition metal(II) ions were studied by UV-vis spectrophotometry. The fluorescent properties of the four complexes were studied with zebrafish, which are expected to be a potential light-emitting material. Ultimately, interaction region indicator (IRI) valuations, Hirshfeld surface analyses, density functional theory (DFT & TD-DFT), electrostatic potential analyses (ESP), and simulations were carried out to further demonstrate the weak interactions and electronic properties of the free ligand and its four complexes.

A dual-channel 'turn-on' fluorescent chemosensor for high selectivity and sensitivity detection of CN¯ based on a coumarin-Schiff base derivative in an aqueous system.

Novel strategies still need to be proposed that can be used to identify and detect toxic environmental pollutants. In this paper, two channels of colorimetry and fluorescence 'turn-on' fluorescent probe 1 (7-hydroxy-8-[(2-hydroxy-phenylimino)- methyl]-4-methylbenzopyran-2-one) for the simple yet highly selective detection of CN¯ have been successfully designed and synthesized. Crystal features of probe 1 were defined using X-ray single crystal diffractometry. Probe 1 showed a strongly colorimetric and fluorescence response to CN¯ that induced obvious naked-eye colour changes in aqueous solution (DMSO/H2 O, 3:1 v:v). In addition, probe 1 for CN¯ detection displayed low detection limits of 3.91 × 10-8 M, which were significantly lower than the 1.9 × 10-6 M maximum level specified by the World Health Organization (WHO) for potable water. The sensing mechanism for probe 1 was attributed to the deprotonation process as shown by 1 H NMR titration. Moreover, based on the visible colorimetry and fluorescence change for probe 1 to CN¯, measurement was performed for simulated water samples containing CN¯. This study provides a broad prospect for solving other pollution problems and promoting the design of new fluorescent materials.

A Highly Selective Turn-on Fluorescent and Naked-eye Colourimetric Dual-channel Probe for Cyanide Anions Detection in Water Samples.

A highly selective turn-on fluorescent and naked-eye colourimetric dual-channel probe for cyanide anions (CN-) has been designed and characterized. In the mixed solution (DMSO / H2O, 9:1, v / v), only CN- could cause an increase in the UV absorption intensity and the corresponding fluorescence intensity increased, and other anions had no significant effect on the probe. After treatment with cyanide in the probe solution, the solution showed a noticeable colour change, from light yellow to purple. Moreover, a fluorescence spectrophotometer can be used to observe that the fluorescence intensity of the solution is significantly enhanced. The response of the colourimetric and fluorescent dual-channel probe to CN- was attributed to nucleophilic addition, and the mechanism was determined by 1H NMR spectroscopy. In addition, this probe was used to detect CN- in actual water samples, including river water, drinking water, and tap water. The spiked CN- recovery rate is very high (97.2%-100.06%), and analytical precision is also very high (RSD < 2%), which shows its feasibility and reliability for detecting cyanide ions in actual water samples.

A highly sensitive and selective fluorescent "off-on-off" relay chemosensor based on a new bis(salamo)-type tetraoxime for detecting Zn2+ and CN.

A new naphthalenediol-based bis(salamo)-type fluorescent probe H4L for Zn2+ and CN- was reported. Probe H4L showed a highly selective fluorescence enhancement toward Zn2+ over other metal ions including Cd2+, and obtained the L-Zn2+complex can only detect CN- in various anions. Their recognition mechanisms were explained by Job plots, fluorescent and UV-vis titrations, and theoretical calculations. The L-Zn2+complex has been synthesized and structurally characterized using Hirshfeld surface analysis, elemental analyses, IR, UV-Vis and fluorescent spectra. Additionally, the relay probe with the wide adaptability of pH range and excellent stability showed highly selectivity for CN- recognition.

Four rare structurally characterized hetero-pentanuclear [Zn4Ln] bis(salamo)-type complexes: syntheses, crystal structures and spectroscopic properties.

Four new hetero-pentanuclear 3d-4f complexes [Zn4(L)2La(NO3)2(OEt)(H2O)] (1), [Zn4(L)2Ce(NO3)2(OMe)(MeOH)] (2), [Zn4(L)2Pr(NO3)2(OEt)(EtOH)] (3) and [Zn4(L)2Nd(NO3)2(OMe)(MeOH)] (4) were synthesized by the reactions of a newly synthesized octadentate bis(salamo)-based tetraoxime ligand (H4L) with Zn(OAc)2·2H2O and Ln(NO3)3·6H2O (Ln = La, Ce, Pr and Nd), respectively, and characterized via elemental analyses, FT-IR, UV-Vis spectroscopy and single crystal X-ray crystallography. The X-ray crystallographic investigation revealed that all ZnII ions were located in N2O3 coordination spheres, and possessed a trigonal bipyramid coordination environment. The LnIII ion lay in an O8 coordination sphere, and adopted a distorted square antiprismatic coordination environment. Furthermore, supramolecular interactions and fluorescence properties were investigated.

Exploration and application of a highly sensitive bis(salamo)-based fluorescent sensor for B4O72- in water-containing systems and living cells.

A highly selective fluorescent sensor H4L based on a bis(salamo)-type compound with two N2O2 chelating moieties as ionophore was successfully developed. Sensor H4L was found to have excellent selectivity for B4O72- over many other anions (Br-, CI-, CN-, CO32-, HCO3-, H2PO4-, HSO4-, NO3-, OAc-, S2O3-, SCN-, SO42-, Hcy (homocysteine) and H2O2), and it exhibited an approximately 150-fold enhancement of the fluorescence response to B4O72- in Tris-HCl buffer (DMF/H2O = 9:1, v/v, pH = 7) solutions. Significantly, its fluorescence intensity was enhanced in a linear fashion with increasing concentrations of B4O72-. The detection limit of sensor H4L towards B4O72- was 8.61 × 10-7 M. The test strips could conveniently, efficiently and simply detect B4O72- ions in Tris-HCl buffer (DMF/H2O = 9:1, v/v, pH = 7) solutions. Furthermore, sensor H4L showed excellent membrane permeability in living cells, and it was successfully used to monitor intracellular B4O72- by confocal luminescence imaging.

Luminescent properties of heterotrinuclear 3d-4f complexes constructed from a naphthalenediol-based acyclic bis(salamo)-type ligand.

Heterotrinuclear 3d-4f complexes with a naphthalenediol-based acyclic bis(salamo)-type ligand have been synthesized and structurally characterized. Spectral titrations clearly show that the heterotrinuclear complexes [Zn2(L)La(OAc)3] (1), [Zn2(L)Ce(OAc)3] (2) and [Zn2(L)Dy(OAc)3(CH3OH)]·CH2Cl2 (3) are acquired by the substitution reaction of the obtained homotrinuclear Zn(II) complex with 1 equiv. of Ln(NO3)3 (Ln3+=La3+, Ce3+ and Dy3+). Two Zn(II) ions are penta- and hexa-coordinated with geometries of distorted tetragonal pyramid and octahedron. La(III) ion is deca-coordinated, adopting a distorted bicapped square antiprism geometry. Ce(III) ion is nona-coordinated with geometry of distorted capped square antiprism as well as Dy(III) ion. The different coordination modes of acetate ions in complexes 1, 2 and 3 lead to different coordination numbers of the lanthanide(III) ions. Furthermore, the structures and fluorescence properties have been discussed.

A new azine derivative colorimetric and fluorescent dual-channel probe for cyanide detection.

A novel azine derivative colorimetric and fluorescent dual-channel probe salicylaldehyde hydrazine-3,5-dibromosalicylaldehyde (1) has been designed, synthesized and characterized. The probe 1 is confirmed to have especial selectivity and good sensitivity on detecting CN- via UV-vis absorption and fluorescence spectrum in aqueous solution (H2O/DMSO, 1:4, v/v). This colorimetric and fluorescent dual-channel probe response to CN- owed to the deprotonation process and established the mechanism by using 1H NMR spectroscopy. Further researches showed that the detection limit of the probe 1 to CN- anions is 8.01×10-9M, significantly lower than the maximum level 1.9×10-6M in potable water from WHO guidelines.

Synthesis, crystal structure and spectroscopic properties of a supramolecular zinc(II) complex with N2O2 coordination sphere.

A new hexa-coordinated zinc(II) complex, namely [ZnL(H2O)2]n, with N2O2 coordination sphere (H2L=4,4'-dibromo-6,6'-dichloro-2,2'-[ethylenedioxybis(nitrilomethylidyne)]diphenol) has been synthesized and structurally characterized by elemental analyses, IR, UV-vis spectra and TG-DTA analyses, etc. Crystallographic data are monoclinic, space group P2(1)/c, a=24.634(2)Å, b=10.144(1)Å, c=7.9351(6)Å, ß=91.371(2)°, V=1982.4(3)Å(3), Dc=2.099 g/cm(3), Z=4. The zinc(II) complex exhibits a slightly distorted octahedral geometry with halogen-substituted Salen-type bisoxime forming the basal N2O2 coordination sphere and two oxygen atoms from two coordinated water molecules in the axial position. The hydrogen-bonding and π-π stacking interactions have stabilized the zinc(II) complex molecules to form a self-assembling infinite dual metal-water chain-like structure with the nearest Zn⋯Zn distance of 4.954(4)Å.

Trinuclear and mononuclear copper(II) complexes incorporating tetradentate 2,2'-[1,1'-(ethylenedioxydinitrilo)diethylidyne]diphenol ligand: Syntheses, crystal structures, spectral and thermal behaviors.

Mononuclear and trinuclear Cu(II) complexes with chemical formula [CuL].CH3OH (1) and [{(Cu(mu-L))2(OAc)2}Cu] (2), where H2L = 2,2'-[1,1'-(ethylenedioxydinitrilo)diethylidyne]diphenol, have been synthesized and characterized by elemental analyses, 1H NMR, IR and UV-vis spectra et al. Crystallographic data of complex 1 reveal the formation of an asymmetric mononuclear structure and a slight distortion toward tetrahedral geometry from the square planar structure, in which the introduction of the non-coordinated methanol molecule lead to the assembly of the 1D chains by hydrogen bonding, Cu...pi and pi...pi interactions. Complex 2 have the elongated square pyramidal geometries for the two terminal Cu(II) ions and an octahedral coordinated geometry for the central Cu(II) ion. In complex 2, two acetate ions coordinate to three Cu(II) ions adopting a familiar syn-syn (muM-O-C-O-M) coordinated fashion. The central Cu(II) ion sits in a crystallographic inversion centre. Therefore, the whole molecule of complex 2 is rigorously centrosymmetric, and forms a 3D supramolecular networks through intermolecular C-H...O and C-H..pi interactions.

6,6'-Dieth-oxy-2,2'-[propane-1,3-diyl-dioxy-bis(nitrilo-methyl-idyne)]diphenol.

The complete mol-ecule of the title compound, C(21)H(26)N(2)O(6), is generated by a crystallographic twofold axis and adopts a trans configuration with respect to the azomethine group. The two benzene rings are almost perpendicular to one another, making a dihedral angle of 89.53 (3)°. In the mol-ecular structure, pairs of intra-molecular O-H⋯N hydrogen bonds generate two six-membered rings. The crystal structure is further stabilized by inter-molecular C-H⋯O hydrogen bonds, which link four adjacent mol-ecules into a network structure.

4,4'-Dimeth-oxy-2,2'-[(butane-1,4-diyldi-oxy)bis-(nitrilo-methyl-idyne)]diphenol.

The title Schiff base bis-oxime compound, C(20)H(24)N(2)O(6), lies across an inversion centre and adopts an E configuration with respect to the C=N bond. In the mol-ecule, the oxime group is roughly coplanar with the benzene ring, forming a dihedral angle of 1.77 (2)°. An intra-molecular O-H⋯N hydrogen bond forms a six-membered ring with an S(6) motif. Weak inter-molecular C-H⋯O hydrogen bonding is present in the crystal structure.

Bis{(E)-2-[1-(eth-oxy-imino)-eth-yl]-1-naphtho-lato-κN,O}copper(II).

In the title complex, [Cu(C(14)H(14)NO(2))(2)], the discrete complex mol-ecules have crystallographic inversion symmetry. The slightly distorted square-planar coordination sphere of the Cu(II) atom comprises two phenolate O atoms and two oxime N atoms from two bidentate-chelate 2-[1-(eth-oxy-imino)-eth-yl]-1-naphtho-late O-ethyl oxime (L(-)) ligands [Cu-O = 1.8919 (17) Šand Cu-N = 1.988 (2) Å]. The two naphthalene ring systems in the mol-ecule are parallel, with a perpendicular inter-planar spacing of 1.473 (2) Å, while each complex unit forms links to four other mol-ecules via inter-molecular methyl C-H⋯π inter-actions, giving an infinite cross-linked layered supra-molecular structure.

Synthesis, structure and spectroscopic properties of two new trinuclear nickel(II) clusters possessing solvent effect.

Two solvent-induced trinuclear nickel(II) clusters, [{NiL(CH(3)OH)}(2)(OAc)(2)Ni].2CH(3)OH (I) and [{NiL(C(2)H(5)OH)}(2)(OAc)(2)Ni].2C(2)H(5)OH (II), have been synthesized by the reaction of a new Salen-type bisoxime chelating ligand of 5,5'-di(N,N'-diethylamino)-2,2'-[(1,3-propylene)dioxybis(nitrilomethylidyne)]diphenol (H(2)L) with nickel(II) acetate tetrahydrate in different solvents. Clusters I and II were characterized by elemental analyses, IR spectra, UV-vis absorption spectra, TG-DTA and X-ray diffraction methods. In clusters I (or II), there are two ligand moieties (which provide N(2)O(2) donors), two acetate ions, two coordinated methanol (or ethanol) molecules and two crystallizing methanol (or ethanol) molecules, which result in the formation of three slightly distorted octahedral geometries around Ni(II) ions. Interestingly, nickel(II) ions in the structures of clusters I and II are all six-coordinated geometry, but clusters I and II are grown up in different solvent. Right because of this, solvent effect cause to their different crystal structures.

2,2'-[1,1'-(Heptane-1,7-diyldioxy-dinitrilo)diethyl-idyne]di-1-naphthol.

The mol-ecule of the title compound, C(31)H(34)N(2)O(4), adopts an L-shaped configuration, in which the naphthalene units are approximately perpendicular, making a dihedral angle of 87.89 (3)°. Intramolecular H-bonds are formed between the OH substituents and the N atoms at each end of the molecule. In the crystal structure, each mol-ecule links six other mol-ecules into an infinite three-dimensional network supra-molecular structure, which is built from one-dimensional zigzag chains via weak C-H⋯π stacking and inter-molecular C-H⋯O hydrogen bonds.

2,2'-[1,1'-(Propane-1,3-diyldioxy-dinitrilo)diethyl-idyne]di-1-naphthol.

The mol-ecule of the title compound, C(27)H(26)N(2)O(4), lies across a crystallographic inversion centre and adopts an l-shaped configuration. Within the mol-ecule, the two naphthalene units are approximately perpendicular, making a dihedral angle of 80.24 (5)°. The two intramolecular O-H⋯N hydrogen bonds, generate S(6) ring motifs. In the crystal structure, every mol-ecule links five other mol-ecules into an infinite cross-linked layered supra-molecular structure via inter-molecular C-H⋯O hydrogen bonds, C-H⋯π inter-actions and π-π stacking inter-actions [centroid-centroid distance = 3.956 (4) Å].

4,4'-Dimethyl-1,1'-[ethyl-enedioxy-bis(nitrilo-methyl-idyne)]dibenzene.

The Schiff base, C(18)H(20)N(2)O(2), which lies about an inversion centre, adopts a linear conformation. The mol-ecules are packed by C-H⋯π inter-actions, forming a two-dimensional supra-molecular network.

2,2'-{1,1'-[Pentane-1,5-diylbis(oxy-nitrilo)]diethylidyne}di-1-naphthol.

The title compound, C(29)H(30)N(2)O(4), adopts a distorted Z configuration with respect to the oxime group, which is almost coplanar with the adjacent naphthalene ring [dihedral angle = 4.11 (2)°]. There is one half-mol-ecule in the asymmetric unit, with a crystallographic twofold rotation axis passing through the central C atom of the -CH=N-O-(CH)(5)-O-N=CH- bridge. Within the mol-ecule, the dihedral angle formed by the two naphthalene rings is 79.08 (3)°, and there are two intra-molecular O-H⋯N hydrogen bonds.